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The Astro-Imaging Thread

Astro-Imaging Questions   41 members have voted

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562 posts in this topic

3 hours ago, FokkerAce said:

nope, no telescope in that picture, I have a Celestron astromaster 70mm refractor 

900 mm long tube? So if you have a 3mm ocular, that's already 300x magnification. Add a 2x barlow and it's 600x, when the twice-your-aperture rule of thumb suggests to stay below ~140x for ideal image quality. No wonder if your view seems blurry.

Edit; you had a diagonal mirror between your barlow lens and ocular? You might try if it's any better without the mirror.

Edited by kurja

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11 hours ago, Green Baron said:

@Epox75: it seems that there is less noise and the filaments are clearer than in the 30sec exposures, what do you think ? Now with 2min exposures the nebula might even be clearer. Yeah, stars are overexposed. There is nothing one can do i think ...

 

There was an open sky this morning, i saw the galaxy high in the sky. The next two days we'll have a phenomenon called Calima, that means high moisture and a lot of desert dust in the lower atmosphere. Thereafter we'll see :-)

@Green Baron The only comparison I can make is with Elephant Trunk where I used 30 sec exposures at 139 gain / 21 offset. While I totally agree with the less noise, that picture I took was way out of focus but anyway yes, the details seem good also at this settings. Next time I want to try one and two minutes exposures with minimun settings (0 gain 10 offset) and see what happens. I also intend to figure out guiding better, I've been lazy so far by always using the st4 port on my camera and attached to the mount, while I should use the Celestron drivers so I can interface the mount to SGPro, configuring PEC, backlash, plate solving and so on. 

We have a similar wind in Italy (did I say already I am from Rome? I lived there 27 years) we call it Scirocco.... everything turns red :) 

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Rome, the eternal city ! Cheers from La Palma, a greean island in the atlantic ocean.

Gain and offset don't tell me nothing. My camera doesn't have these settings. It can only take pictures at a given temperature for a given exposure time. I assume they are settings for the signal amplifier/processor to do something ? Like ISO settings on a dslr ? What i know from dslr photography is that a chip has its highest dynamic range (in terms of light values, lv) when the signal is unamplified. That means for a dslr, if a chip is designed with an iso of 200, it will have the best performance at iso 200. Every higher setting will make things worse, like the noise is equally amplified with the signal.

Good luck !

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14 hours ago, kurja said:

900 mm long tube? So if you have a 3mm ocular, that's already 300x magnification. Add a 2x barlow and it's 600x, when the twice-your-aperture rule of thumb suggests to stay below ~140x for ideal image quality. No wonder if your view seems blurry.

Edit; you had a diagonal mirror between your barlow lens and ocular? You might try if it's any better without the mirror.

there is a diagonal mirror between the tube and the eyepiece

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4 hours ago, Green Baron said:

Gain and offset don't tell me nothing. My camera doesn't have these settings. It can only take pictures at a given temperature for a given exposure time. I assume they are settings for the signal amplifier/processor to do something ? Like ISO settings on a dslr ? What i know from dslr photography is that a chip has its highest dynamic range (in terms of light values, lv) when the signal is unamplified. That means for a dslr, if a chip is designed with an iso of 200, it will have the best performance at iso 200. Every higher setting will make things worse, like the noise is equally amplified with the signal.

Good luck !

Yes Gain/offset can be compared to the ISO of DSLR even if I have to admit I am bit ignorant (let's say very ignorant) about the technical details. Trial and error for the win! :) What I read about the AI1600MM-Cool is that even at highest settings keeps the noise acceptable and there are also settings that give extremely low noise (like the 76/15 or the 0/10). 

I finally integrated the data from 4 days ago to the Fireworks Galaxy. 11.2 Hours - 5.2 for Luminance, 6 for RGB. Luminance is a combination of the Lumicon Deepsky filter and the UV/IR Cut Baader. 

Edit: can you spot that wierd object almost at the right center side of the picture? It's looks like something enveloped by a ball of nebulosity anyway is not an artifact because it appears like this in all the pictures and I cannot find anything about it. 

eybWXe6.png

Technical card: 

http://www.astrobin.com/299244/J/

Edited by Epox75
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I was getting some star fields a little bit ago, and a super bright meteor flew over, like magnitude 0 to around -1 scared the ever living crap out of me when i first noticed it....

Edited by FokkerAce

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Are there any objections against the Lagoon Nebula?

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7 minutes ago, Adstriduum said:

Are there any objections against the Lagoon Nebula?

not really

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@Green Baron I have a question to ask if you don't mind. You seem to know your newtonians so I would like to hear from you before moving the CN community :) 

How does this look? scope is collimated in this picture but i'm more interested in knowing if the secondary is in a right position. Yellow circle is the hole on my cap centered in the primary donut, the red circle is the back of my cap, so the focuser hole and the green one is the secondary as I see it (circle might not be perfectly correct because of the light). For info: I cannot move the secondary further back, it basically at its max. 

bp6qXeH.jpg

Edited by Epox75
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I feel honoured :-) I probably have my knowledge from the same sites as you. Example (not regarding offset) Or this. Newtons can be demanding, another reason why i got me an apo :-)

A assume that your eyepiece is centered in the drawtube and the drawtube of the fcuser is rectangular to the optical axis. Then this looks to me as if the secondary is not quite centered towards the drawtube. If this is because of the offset then it might be okay, but afaik the offset goes towards the focuser and the main, not away from the focuser. Also i see the focuser tube getiing in the way, which might lead to partial vignetting. Maybe you can find a setup where it is as far out as possible ?

But by all means please do ask on CN and let us know the opinions of the savants there :-) !

 

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@Green Baron Thank you! This makes things a bit clearer now. Don't worry about the focuser, it goes completely off the tube after focusing :P  Anyway if I understood correctly you mean this right? where red is wrong offset direction and green correct? If i am correct how do I rotate the secondary that way...  by loosing the collimation screws and moving the center one?

chCyuvr.jpg

A little update with a more clear picture: collimation went off a bit because I was moving screws around. I think cap and draw tube are in line, and my line of sight goes straight into it (rail is my reference). The problem is that I cannot create an offset that goes on the opposite side because i can't move the secondary further back :( So i'm wondering If i should drill four more holes for the spider arms 1 or 2 cm closer to the aperture. 

xWMYqxm.jpg

 

 

Edited by Epox75

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